Chasing die



July 7, 1925. 1,545,162

G. E. -NELSON CHASING DIE I Filed May 10, 1922 //v VENTOR susmv E. NELSON.

ATTORNEYS.

Patented July 7, 1925.

UNITED STATES GUSTAV E. NELSON, OF SAN FRANCISCO,

CALIFORNIA, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, T FRANK T. OROURKE, 0*]? SAN FRANCISCO, CALIFORNIA.

CHASING DIE.

Application filed May 10, 1922. Serial No. 559,740.

To all whom it may concern:

Be it known that I, GUSTAV E. NELsoN, a citizen of the United States, residing at the city and county of San Francisco and State of California, have invented new and useful Improvements in Chasing Dies, of which the following is a specification.

This invention relates to a metal working tool and particularly pertains to a die for chasing screw threads.

In the operation of various machines, and. particularly in connection with automobile construction it often happens that threads of screws are mutilated due to wear or jamming of parts. In this case it is advantageous to straighten the threads out so that the screw may be again used without replacing it. It is the principal object of the present invention, therefore, to provide a die which may be readily adapted to screws of various pitch and diameter, and which die may be manipulated to clear the threads and place them in condition for further use, said die being especially adapted for truing up the threads of automobile axle spindles.

The present invention contemplates the use of a frame structure carrying a plurality of radially movable die members arranged in sets and which members are so mounted as to be readily clamped into the gullet of the threads for a cutting operation, irrespective of the diameter of the screw or the pitch of the thread.

The inventionis illustrated by way of example in the accompanying drawings in which: 1 1

Fig. 1 is a View in transverse section through the die, showing its application to the thread of an automobile spindle.

Fig. 2 is a view inside elevation showing the die with parts broken away for the sake of clearness.

Referring more particularly to the drawings 10 indicates a die bit which may be formed of tool steel, and has a cutting edge 11. This edge is here shown as being suitably formed for. use on conventional V-shaped threads, although it will be understood that other forms of threads may be operated upon if desired. It is preferable that the bits shall be arranged in sets disposed in radial relation to the center of the die structure. As shown in Fig.- 1 of the drawings, there are two bits vin each set.

although it is to be understood that any number of bits may be used as convenience dictates. The bits of each set are yieldably mounted for lateral movement upon pins 12 while a spring 13 is disposed between the bits and permits them to yield so that their cutting edges may register with the threads of the screw, irrespective of the pitch of the threads. The plus 12 pass through slotted openings, 14 in disks 15 and 16, which openings extend longitudinally of the bits, the outer ends of the pins pass through arcuate cam slots 17 which are formed in bit actuating plates 18 and 19. The disks 15 and 16 are interposed between the sets of bits and the outer plates 18 and 19. By reference to Fig. 2 it will be seen that the arcuate slots 17 are disposed eccentric to the center of the plates; thus as plates 18 and 19 are rotated relative to the disks 15 and 16 they will cause the bits to move radially of the die structure. The dies are guided in their radial movement between guide blocks 20 and clamping blocks 21. The guide blocks 20 are secured between the disks 15 and 16, serving as spacers for the two plates and at the same time providing radially disposed guide faces along which the bits may slide. The locking blocks 21 are triangular inshape, having one face resting against the back of an adjacent guide block and the other face resting against the edge of a die bit, The outer edges of the locking blocks 21 are formed with cam faces 22 against which rollers 23 may act. These rollers will tend to force the locking blocks 21 inwardly, causing the die bits to be wedged and locked in position.

The rollers are carried upon pins 24 which extend through the rings 25. The rings are disposed around the circumferential edges of the plates 18 and 19 and are adapted to rotate relative to these plates and concentric therewith. The disks 15 and 16 are of larger diameter than the inner bores of the rings and thus hold them in their rotatable positions. Extensions 26 are formed as a part of the rings 25 and carry a bar 27 through which a clamping screw 28 projects. This screw extends into a nut carried by extensions 30 of the disks 15 and 16.- Thus, by tightening the screw 28 the disks 15 and 16 with their wedge blocks 21 will cause the rollers 23 to engage the cam faces of the wedge blocks, thereby locking the bits in an adjusted position. The radial adjustment of the bits is made by movement of the plates 18 and 19 in relation to the disks 15 and 16. The plates 18 and 19 may be Simultaneously rotated around the central axis of the die structure by a yoke 31 which is rigidly secured to the plates and extends outwardly around the'rings 25 to serve as a grip by which the plates may be simultaneously moved.

In operation of the present invention the plates 18 and 19 may be rotated so that the pins 12 are in their outermost positions in the camslots 17 At this time the die bits will be moved to their outermost positions as guided along the blocks 20. A screw may then be inserted through the central opening 32 of the structure, after which the disks 18 and 19 may be rot-ated in the direction of the arrow a, as indicated in Fig. 2. This rotation of the plates 18 and 19 relative to the remainder of the structure will cause the pins 12 to travel inwardly along the cam slots 17 and will thus simultaneously force all of the die bits inwardly to dispose their cutting edges tangentially of the circumference of the screw and within the gullets oi the threads. If it so happens that the pitch of the threads is at variance with the normal positions of the die bits of each set, these bits will automatically adapt themselves to the threads due to their yielding mountings upon the pins 12, thus making the device universally applicable to screws of varying diameters and thread pitch. After the cut ting faces, of the bits have been securely positioned within the gullets of the threads the screw 28 maybe rotated tending to draw the arms 26 and 30 together.

tween the rings 25 and the disks 15 and 16. Thus the rollers 23 will force against the cam faces 22 of the lock wedges 21. This will cause these wedges to be forced inwardly and will clamp the die bits between adjacent lock wedges 21 and guide blocks 20. After the bits have been'clamped in position the structure may be rotated by means of an arm 33 which is secured to the disks 15'and 16.

It will thus be seen that the device here disclosed may be readily used for straightem ing up and renewing screw threads which may vary in pitch and which are formed on cylinders varyingin diameter, the structure being readily disposed in operative position and easily removed therefrom.

YVhile I have shown the preferred form of my invention as now known to me, it will be understood that various changes may be made in the combination, construction and arrangement of parts by those skilled in the art, without departing from the spirit of the invention as claimed. I

Having thus described my invention what This action I will cause relatlve rotative movement be- I claim and desire to secure by Letters Patent is: V

' 1. A structure comprising a pair of con centric disks, a plurality of die bits mounted between said disks and guided for radial movement therebetween, pins upon which said die bits are loosely mounted, said pins extending through radial slots in said disks, an actuating plate at each side of the struc ture, said'plates being connected whereby they may be rotated in unison with relation to said disks, said plates having cam slots formed therein with which said pins engage whereby turning movement of the plates relative to the disks will afiect the radial holding the bits in a normal position, said bits extending'through radial slots in said disks, an actuating plate at each side of the structure, said plates being connected whereby they may be rotated in unison with relationto the disks, said plates having cam slots formed therein with which said pins engage whereby turning movementfof the plates relative to'the disks will affect the radial position of the die bits.

' 3. A die structure comprising a pair of concentric disks, a plurality of guides formed between said disks, die bits disposed in said guides and guided for radial movement thereby, each of said guides including a wedge member, an actuating plate at each side of the structure, said plates being connected whereby they may be rotated in unison with relation to thedisks', said plates having cam slots formed therein with which said bits engage whereby turning movement of the plates relative to the disks will infect the radial position of the die bits, and means operable lndependently of said actuating plates for operating the wedges of said guides to clamp the die bits in a set position.

4. A die structure comprising a "pair of concentric disks, a plurality of guides formed between said disks, die bits disposed in said guides and guided for radial movement thereby, each of said guides including a wedge member, an actuating plate at each side of the structure,said plates being connected whereby they may be rotated'in unison with relation to the disks, said plates.

having cam slots formed therein with which said bits engage whereby turning movement of the plates relative to the disks will afieict the radial position of the die bits, means operable independently of said actuating plates for operating the wedges of said said rings and said disks for causing rotatguides to clamp the die bits in a set position, ing movement of the rings relative to said said means comprising cam surfaces on said disks whereby to operate said Wedges and 10 Wedges, a pair of rings mounted concentric cause them to clamp said die bits in a set to said actuating plates and carrying rollers position.

engageable with the cam surfaces on said wedges, and an operable connection between GUI'TAV l) N Eli-SON. 

